Seattle Seahawks center Justin Britt, right, stands next to defensive end Michael Bennett as Bennett sits on the bench during the singing of the national anthem before the team's NFL football preseason game against the Minnesota Vikings, Friday, Aug. 18, 2017, in Seattle. (AP Photo/Stephen Brashear)

SEATTLE - Super Bowl champion and Seahawks' defensive end Michael Bennett said he was assaulted and threatened at gunpoint by police during a chaotic incident in Las Vegas last month, and he now is exploring his legal options - including filing a federal civil rights lawsuit against the city of Las Vegas.

Bennett said he was singled out for "for doing nothing more than simply being a black man in the wrong place at the wrong time."

Las Vegas police have opened an internal investigation into Bennett's allegations, though he has not filed a formal complaint with the department. A top police official denied race played any part in the incident.

In an open letter posted Wednesday on social media, Bennett detailed the incident in which Las Vegas police forced him to the ground, handcuffed him, pointed a gun at his head and threatened to "blow my (expletive) head off."

"This was a traumatic experience for me and my family," he said Wednesday afternoon at a Seahawks-sponsored news conference that ended when he became emotionally overwhelmed and had to leave the room.

In a news conference Wednesday, Las Vegas Undersheriff Kevin McMahill detailed what police know about the incident and showed a five-minute video of events leading up to Bennett being detained.

McMahill said the incident began after a call came in about 1:30 a.m. Aug. 27 about an active shooter in a Las Vegas casino. The call happened about three hours after the Mayweather-McGregor fight.

Officers found thousands of people running for cover in the Las Vegas casino and nightclub, according to McMahill.

McMahill said officers found Bennett crouching inside near a gaming machine and as officers approached, Bennett began to run and jumped a wall, landing on the street outside.

That is when officers detained Bennett for about 10 minutes, McMahill said. The officers who detained him had their guns out.

Bennett was not armed.

McMahill said a police supervisor explained the situation to Bennett and that he accepted the explanation.

Police later determined there were no shots fired in the casino and that the active shooter call was unfounded, according to McMahill.

McMahill rebutted Bennett's allegation of biased policing.

"I see no evidence that race played any role in this incident," he said.

Police have at least 126 videos to review and are asking for more from the people who were in and outside the casino.

But McMahill said the officer who detained him did not activate his body camera.

Bennett said he was walking back to his hotel after watching the Mayweather-McGregor fight on his day off Aug. 26 when he and several hundred others heard what sounded like gunshots.

As he and the others ran from the sound, looking for safety, police singled him out and pointed their guns at him, Bennett said.

Police then ordered Bennett to get on the ground and not move. As he lay there, one officer placed a gun to Bennett's head and warned him that if he moved he would blow his head off.

He was then assaulted and handcuffed so tightly that his fingers went numb. As he lay there, Bennett said he was afraid for his life and wondered if he would ever play with his kids again or be able to kiss his wife and to tell her how much he loves her.

"The whole time all I could think about was my wife and my kids," he said at Wednesday's news conference. "I wasn't thinking about the Super Bowl - I was thinking about my wife and children and how much they mean to me."

TMZ obtained video that was shot outside Drai's Nightclub, where one officer can be seen taking position on a balcony while another officer handcuffs Bennett on the street.

In the video, Bennett screams out, "I wasn't doing nothing man! I was here with my friends! They told us to get out, everybody ran!"

Eventually Bennett was put into the back of a patrol car "for what felt like an eternity" until officers finally realized he was a famous NFL player. He was then let go without any kind of explanation or apology for what he had been through, Bennett said.

Bennett's social media posting is seen here ... Warning: Contains obscenity and other graphic language ...

Bennett said he can only imagine what other black people - who are not famous - feel when confronted with deadly violence.

"The system failed me. I can only imagine what Eric Garner, Michael Brown, Trayvon Martin, Tamir Rice and Charleena Lyles felt," he wrote.

Bennett said he has retained civil rights attorney John Burris "to investigate and explore all my legal options including filing a civil rights lawsuit for the violation of my civil rights."

Burris released a statement saying, "It is important to note, Mr. Bennett was unarmed, sober and not involved in any altercations or dispute at the time the police officers arrested and threatened to use deadly force against him. ... The officers’ conduct is particularly outrageous in that there was no basis upon which to select Mr. Bennett from a crowd of people all running for their lives. He did nothing wrong."

"We think there was an unlawful detention and the use of excessive force, with a gun put to his head," Burris told The Associated Press. "He was just in the crowd. He doesn't drink or do drugs. He wasn't in a fight. He wasn't resisting. He did nothing more or less than anyone in the crowd."

Burris said Bennett waited to make public his account of the incident until after Burris contacted Las Vegas police last week by letter and email, seeking police records of Bennett's detention.

At Bennett's news conference Wednesday, Bennett said he decided to speak to the press about the incident because "so many pepole had the experience I had and they're not here to tell their story."

"It's an emotional moment for me," he said. "Did I ask for this moment? No - it just happened to be me." He said if the officer had followed through on his threat, "you guys would be wearing a patch with No. 72 on it."

Bennett also said he is glad of the support he has had from the Seahawks organization since the incident. "If I didn't have their support, I wouldn't have the strength to come up here (to the podium). ... It's bigger than me. There's a lot of things going on in this world."

A spokesperson for Burris said he has asked for Las Vegas police to release video and the the names of officers involved.

Bennett has been one of the most vocal players in the NFL about the protests started by former 49ers quarterback Colin Kaepernick, which began in opposition to the unequal treatment of minorities by law enforcement.

Bennett now has a personal reason to continue those protests.

"I try to tell my daughters every day that they matter," he said at the end of his news conference before choking up and walking away from the podium.

NFL Commissioner Roger Goodell released a statement on Wedensday saying: "Michael Bennett represents the best of the NFL - a leader on his team and in his community. Our foremost concern is the welfare of Michael and his family. While we understand the Las Vegas police department will address this later this evening, the issues Michael has been raising deserve serious attention from all of our leaders in every community. We will support Michael and all NFL players in the communities they loyally serve and fair and equal treatment under the law."